1. Field of the Invention
This invention relates generally to the field of manually powered tools and, more particularly, concerns manually-operated terminal wire connecting tools actuated by squeezing a movable lever to produce a rotating motion for twisting or untwisting wires about terminal posts.
2. Description of Prior Art
Terminal wire connecting tools can be used to give a solderless contact by tightly twining wire around a given surface. They can be used to establish electrical contact, to mechanically link objects together or for a number of other purposes. Generally, such tools are electrically, pneumatically or manually powered and use mechanically interconnected gears to turn a terminal wire connecting bit.
The present invention is primarily concerned with manually-operated terminal wire connecting tools, such as those used by telephone repairmen, electronic technicians, service men and others who are sometimes without the luxury of electrical power.
Often in manually-operated tools, a lever or handle is pivotably mounted on the frame of the tool, and a gear rack is located on one end of the lever, usually opposite the pivotal mounting. When squeezed, the lever moves "toward" the rear of the tool in a manner similar to a trigger being squeezed on a gun. The movement of the lever causes movement of the gear rack which drives a spur gear meshed with the gear rack resulting in driving the rotating mechanism of the tool. The speed and number of rotations delivered can usually be controlled by controlling the rate and the amount of force applied by hand.
It has been found that currently available manually-operated terminal wire connecting tools are prone to wear, especially in the areas of contact between the gear rack and the spur gear and in the area of the frame where the lever is pivotably mounted.
Normal friction and stresses occasioned during use are the major factors contributing to wear, though in part wear can be attributed to the uneven squeezing pressures exerted by the action of a human hand. Squeezing movements are not as uniform or one directional as the movement produced by an electrical motor in power tools, and lateral pressures shifting sporadically from side to side contribute to wear. When the opposing teeth of the spur gear and gear rack are shifted against each other, the opposing gear teeth can become worn or rounded, increasing the likelihood of slippage or disengagement. As time progresses, the tools can develop an annoying "play," that decreases their efficiency and makes them more difficult to use.
A separate problem associated with manually-powered terminal wire connecting tools is the close machining tolerances required during their manufacture, especially tolerances associated with mounting the lever on the frame, and those required to ensure an accurate gear tooth profile. Close tolerances increase manufacturing costs.
Hence, a manually-operated terminal wire connecting tool which can compensate for wear, eliminate "play" as it develops, and which does not require close machining tolerances during manufacture is very desirable, and a substantial savings in cost could be enjoyed by both manufacturer and consumer.